Surprising Facts About Dehydration, Heat Exhaustion and Heat Stroke

Living in South Florida creates many self-proclaimed “experts” about the heat index, dangerous temperatures and related illnesses, such as dehydration, heat exhaustion and heat stroke. But, some facts about our body’s reaction to hot weather may surprise even the most “expert” among us.

As the peak of South Florida’s treacherous summertime heat approaches, a real expert on heat-related illness, Baptist Health Primary Care’s Gabriel Solti-Grasz, M.D., explains that what you might think you know about the effects of high temperatures and humidity on the body may not be enough to prevent a dangerous health crisis.

“Heat stroke is the end of the story,” Dr. Solti-Grasz said. “The beginning of the story is where we can prevent a grave situation from quickly evolving.”

Preventing Dehydration

Dr. Solti-Grasz says preventing dehydration is key, and there’s a simple recipe for that – H2O.

“People often don’t drink water or liquids until they begin to feel thirsty,” he said. “But thirst is an indication that the process of dehydration has begun.”

Dr. Solti-Grasz recommends drinking water before going out in the heat and continuing to drink water regularly for the duration of time spent outside. If exercising in the heat, he recommends drinking a sports drink with electrolytes to replenish nutrients, such as salt and potassium. These, he says, are lost quickly during exertion in high temperatures or high humidity. Electrolytes help your body function properly, including regulating heart rate and maintaining a healthy body temperature.

He also points out that dehydration, and the subsequent progression to heat stroke, can occur when it’s not necessarily hot, if you’re not replenishing fluids regularly.

“When you start to feel symptoms, it’s too late for prevention, you must switch to replenishment and recovery,” he said.

Signs of Dehydration

• Thirst – As soon as you feel thirsty, know that dehydration is underway.
• Reduced urination – If you don’t have to urinate while in the heat, you need to drink more fluids.
• Headache – Once your head starts to hurt, you’re likely entering the next phase of heat-related illness – heat exhaustion.

With any of these signs, or a general sense of not feeling well while in the heat or during exertion, Dr. Solti-Grasz advises to seek relief by going into an air-conditioned or shaded environment to cool the body down. He also recommends drinking water or a sports drink slowly to replenish lost fluids, while preventing nausea or vomiting.

Heat Exhaustion

Heat exhaustion, Dr. Solti-Grasz says, is the middle category of heat-related illness and can quickly turn into heat stroke, if not treated.

Symptoms of Heat Exhaustion

• Headache – As a heat-related illness progresses, a headache may become more severe.
• Dizziness or lightheadedness – Shakiness and a feeling of instability or weakness often accompanies heat exhaustion.
• Nausea or vomiting – The body prepares for systemic shut down by purging contents in the stomach, including liquids, which can lead to a faster deterioration of health through further dehydration.
• Reduced urination – As your body tries to regulate your temperature, it begins to shut down organs, like your kidneys. This can lead to acute kidney injury, Dr. Solti-Grasz warns.
• Fainting – This is the body’s way of taking over to protect vital organs against loss of fluids.

With symptoms of heat exhaustion, Dr. Solti-Grasz advises seeking medical attention right away, including calling 911, so fluids can be given through an IV as soon as possible. He does not recommend drinking liquids at this stage, as fluids may enter the lungs through the trachea, or airway.

Heat Stroke

As heat illness progresses, heat stroke can occur. With heat stroke, Dr. Solti-Grasz says, the body tries to lower its internal temperature by systematically shutting down organs to protect the heart and brain.

Signs of Heat Stroke

• Low blood pressure – The body limits blood flow from extremities and redirects it to vital organs.
• Perspiration stops – When you stop sweating, your body has begun to shut down certain systems and functions to preserve life.
• Cold or clammy skin – As blood is redirected to vital organs, the skin becomes cooler.
• Shock – All of the above symptoms, Dr. Solti-Grasz says, signal shock, a life-threatening condition that occurs when the body enters survival mode.

“Heat stroke is a grave condition,” he said. “Often people use this term interchangeably with heat exhaustion, but heat stroke can be fatal, so it’s important to focus on preventing dehydration first to avoid the progression to heat stroke.”

Higher Risk Individuals

Even South Floridians who have grown more accepting of the heat should understand that they run the risk of serious heat-related illnesses, including heat stroke, without taking protective measures.

Dr. Solti-Grasz notes that children and the elderly, as well as those individuals with cardiovascular or liver disease, are most susceptible to heat-related illnesses.

“For these groups, the process of dehydration occurs much faster, as the body’s compensatory measures don’t work as efficiently,” he said, adding that these individuals should be closely monitored while in the heat and high humidity.